The present invention relates to absorbent articles, and more particularly to disposable diapers.
A various assortment of disposable diapers have been proposed for use on infants, and have become increasingly popular since they may be discarded after a single use and need not be laundered. Such diapers are normally constructed having a fluid impervious backing sheet, a fluid pervious cover or top sheet, and an absorbent pad between the backing and cover sheets. Many of the current disposable diapers have also been provided with tape fasteners which are usually in the form of a pressure-sentitive tape strip having a first end section secured to the backing or cover sheets, normally the former, and a second end section which is used to secure the diaper about the infant.
Of course, a critical factor in the suitability of the diapers is the cost to the consumer, since the diapers are not reused, and relatively thin materials have been proposed for the diaper backing and cover sheets in order to reduce the cost of the required manufacturing materials. However, it has been found that considerable forces are applied to the tape strips during placement and use of the diaper, and, in many instances, the applied forces are sufficiently large to cause rupture of the thin backing or cover sheets at the point where the tape strips are secured to the diaper. Thus, the tape strips are frequently torn from the diapers, resulting in a relatively useless diaper without a suitable tape fastener.
In the past, all of the tape strip backings, such as paper, cloth, spun bonded polyolefin, or reinforced polyethylene, sold on diapers known to the applicant have been relatively inextensible, e.g., the backings have an ultimate elongation of approximately 3-6%, or have otherwise required relatively large forces to obtain extensibility. In either event, it has been discovered that the relative inextensibility of the tape strips contributes significantly to the incidence of tape strip rupture or shear from the diaper. On the other hand, a tape backing which is too extensible, such as rubber, exhibits excess stretch during attachment to the diaper which makes placement of the fastener difficult, may result in a loose fitment of the diaper about the infant, and such a fastener may require different components which increases the cost of manufacture.